Inclinometer



Nov. 3,` 1936. E. cHRlsTENsEN INCLINOMETER Filed Nov. 2o, 1934l Patented Nov. 3, 1935 UNITED STATS PATENT OFFICE Claims.

My invention relates to devices for indicating rate of climb in an airplane or automobile in which the grade of the vehicle with respect to the horizontal is indicated by fluid in v.a trans- 5 parent tube.

Broadly speaking such devices are old and many attempts have been made to construct a suitable instrument of this general character that would reliably and correctly'indicate grade and rate of climb or descent.

While some of these various attempts have met a modicum of suc-cess the stumbling block has always been to damp the movement of the indicating fluid so that surges, shocks and abrupt l5 changes would not produce such a violent movement of the indicating uid as to render the device substantially useless.

The objects of my invention may be succinctly stated in their major features as follows:

2b An inclinometer of the character indicated with an efficient damping -device that does not go into action on slight changes of grade but will positively damp the flow of fluid with abrupt changes or in the event of shocks so that the 25 reading may be relied upon.

Another object of my invention is a two fluid inclinometer of this type that will automatically readjust itself should the instrument be turned upside down or in any other manner be turned 30 from its normal position to such a degree that normal positions of the tvvov fluids are disarranged.

A further object of my invention is an air chamber in connection with the fluid containing 35 tubes and so arranged that it will take care of the normal expansion and contraction of the fluids due to temperature changes but which will in no way influence the reading of the instrument.

Another object of my invention, which is con- 40 sidered among the most important ones, is a damping device for the purpose hereinbefore indicated and in which the kinetic energy developed by a surge in fluid in the instrument will be applied to some extent, at the same time, to both 45 ends of that column of fluid that serves for indicatingr grade.

These and other objects are attained by the structure illustrated in the accompanying drawing and described in the specification.

In the drawing:

Fig. I is a side view of the liquid containing portion of the instrument with one-half of the supporting casing removed and mounted in an 55`r adjustable mounting, adapting it in this case to be mounted on a steering column as shown in Fig. II;

Figs. II and IV are details of the mounting of the instrument shown in Fig. I, drawn to a smaller scale; 5

FigjIII is an enlarged View of the interior of the upper part of Fig. I enlarged to clearlyk indicate its structure and mode of operation;

Fig. IV includes an enlarged View of the indicating part of the instrument; 10

Fig. V is the valve member E in plan;

Fig. VI is a longitudinal sectional elevation of the element I6 containing the valve 6 and showing construction for holding it in place;

Fig. VII is a top view of Fig. VI;

Fig. VIII is a broken away part of an orthographic projection of Fig. VI;

Fig. IX is a broken away part oan orthographic projection of the lower part of Fig. VI

in proper position; and y Fig. X is a section on the line X--X of Fig. VI.

Referring to Fig. I, a generally triangularV shaped fluid container I, having a base portion 8,

a transparent indicating side leg 20, a reservoir portion Iii, and a central bisector tube II, is` mounted in a two part casing I2, the two parts being held together by the bolt I3 and the wing nut Ill, sho-wn to be pivotally mounted on the arm I5.

The bisector tube II, is arranged to contain. the removable valve support I6, which is preferably a close fit within the bisector tube II,l and within which it wil be cemented by a heat sensitive cement so that it may be removed on occasion Without breaking the glass of which the whole liquid containing part is preferably made.

The valve support I6, has an internal passageway I6a, within which is anchored a double acting surge valve member 6. This latter is preferably made of a thin wafer of steel having a thickness of the order of thousandths of an inch. The valve 6 co-operates with the ports 6a, 6b, 6c, and Bd. A conventional way of supporting the valve 6 in position is indicated by the set screws 9.

has greater volume than the remaining portions 551 of the uid container and therefore in case of surges it will dominate the movement of fluid in the entire apparatus.

Considering the relative positions of the fluids shown in Fig. I and with the instrument at rest the mercury will be level in all of the several legs though it has not been shown level in the passageway I6a above the bisector tube II because that part is considered to be opaque and an attempt to show it would be confusing.

The upper portion of the fluid container I, contains a stopper I'I, which is preferably a cork sealed in with sealing wax at I8. The cork I1 rests upon the top of the valve support I6, liquid tight.

It will be noted that a gradual movement of incline of the instrument will not affect the valve 6, and the level of the mercury or indicating portion of the fluid will gradually change according to the level but should a surge occur the valve will immediately move to control the ports 6a, 6b, or 6c and 6d and shut them off in the direction of the surge. The passageway up through the bisector tube I I and past the valve 6, however, remains open so that the surge influence, be it pressure or suction, will be felt at both ends of the index tube 20, though the force will be unbalanced to some extent. This constitutes the damping arrangement and as soon as 'the indicating fluid in 20 moves slowly to its proper position, the valve 6 being resilient will resume its normal disengaged position as shown in Fig. I and the instrument will register the true grade. The valve 6 will move to close the ports 6a and 6b if the surge is in one direction, or 6c and 6d if the surge is in the other direction.

The passageway |60. extends all the way around the valve 6 and is in open communica- A tion with the bisector tube II and its purpose is to provide a restricted flow passageway when the surge valve has operated. Considering Fig. I, and assuming it to be moving at high speed toward the right. When very rapidly decelerated, the reed-like valve 6 will first close port 6c and afterwards 6d if the resultant surge is strong enough; this action is obvious from the angularity of the valve, which of necessity must be very iiexible. See Fig. VI. The inertia of the liquid in the several tubular parts to the right of the bisector tube II will be substantially balanced through the passage I 6a; the top of the indicator tube will be momentarily sealed off by the valve 6; and motion of the fluid in the indicator .tube and that part of 'I to the left of the bisector II, will be momentarily almost completely damped; thus deceleration will have little visible effect on the indicator tube.

In case of rapid acceleration the Valve 6 closes against the ports 6a and 6b in the same manner as heretofore described when the superior Weight of the fluid in the reservoir portion will be felt at both ends of the indicator tube, also tending to neutralize the inertia effect.

It will be observed that by making the valve 6 after the schematic plan shown in the drawing, a surge movement in either direction will cause a movement of the Valve to close the corresponding ports so that the valve is double acting.

This instrument constructed as shown is particularly suitable for airplane use. An airplane can be and frequently is ilown upside down, and it will be noted that the several legs of the instrument connected across the top and. at the bottom and by the bisector tube II and the passageway IGa, form efficient equalizing means permitting the two fluids to resume their proper position and relationship immediately on the instrument assuming its proper position.

It will be noted that the space above the lighter fluid may be either a partial vacuum or may contain air at atmospheric pressure as of the temperature at which the tube was charged with fluid.

These chambers accommodate the thermal expansion of the fluids and the upper ports 6a and 6c control communication between the two air chambers, it being understood that the sides I6c and Id are hermetically sealed to that portion of the liquid container 'I with which they contact.

I am aware that two-uid inclinometers have been attempted heretofore, that restrictions have been placed in passageways to act as dampers to the movement of the fluid, but I am not aware that my bisector type has ever been used whereby surge influence will appear at both ends of the indicating column of iiuid, nor is it apparent that a double acting Valve of the character shown and described here has ever been applied to an instrument of this character.

Having thus fully disclosed the principles governing the construction of my new inclinometer, what I claim as new and desire to secure by Letters Patent, is,-

l. A fluid type inclinometer dened in part as a triangular tubular element, comprising an indicator tube, an oppositely disposed tubular reservoir portion, a bisector tube, an apex forming communication means between the tops of the named members, said communication means being formed to provide oppositely disposed ports, and a double acting surge valve mounted for movement to control the ports under the inuence of surge of contained fluid.

l2. The combination characterized in claim 1 and including an air chamber in the apex immediately above the ports.

3. A liquid type grade indicator, comprising an indicator tube, an oppositely disposed reservoir, normally open communication means between top and bott-om of said members, said top communication means being formed to provide a plurality of pairs of oppositely disposed ports, a double acting surge valve mounted for movement to control said ports under the influence of fluid surge and a bisector tube to relieve the surge.

4. A liquid type grade indicator, comprising an indicator tube, an oppositely disposed reservoir, normally open communication means between top and bottom `of said members, said top communication means being formed to provide a plurality of oppositely disposed ports, a double acting surge valve mounted for movement to control said ports under the inuence of fluid surge and a normally open bisector tube within which said valve is operatively mounted.

5. A liquid type inclinometer defined in part as a bisecte-d obtusely triangular tubular liquid container, comprising an indicating tube, an oppositely disposed reservoir tube, normally open apex communication means at the top of the reservoir and indicating tubes, an open base tube connecting the respective bottoms thereof, a bisector tubular member between said base and said apex and a double acting surge valve in said bisector that is arranged to control said apex communication under the influence of fluid surge.

EMIL CHRISTENSEN. 

